Personal audio devices, including wireless telephones, such as mobile/cellular telephones, cordless telephones, mp3 players, and other consumer audio devices, are in widespread use. Such personal audio devices may include circuitry for driving a pair of headphones or one or more speakers. Such circuitry often includes a power amplifier for driving an audio output signal to headphones or speakers. Generally speaking, a power amplifier amplifies an audio signal by taking energy from a power supply and controlling an audio output signal to match an input signal shape but with a larger amplitude.
In many devices, a boost converter may serve as a power supply to supply a power amplifier with electrical energy for the power amplifier's output stage. As known in the art, a boost converter is a power converter that converts a direct-current voltage, often a voltage output by a battery, to a larger direct-current voltage. Typically, substantially all of the current delivered by the power amplifier to the load (e.g., headphone or speaker) is supplied by the boost converter.
Many static and dynamic methods exist for limiting a boost converter's power consumption of a battery in order to protect a device from consuming too much power or causing a drop in the battery supply voltage down to a level susceptible to browning out a device. However, if the boost converter limits its consumption from the battery in order to protect the battery, the boosted supply voltage generated by the boost converter is likely to lose regulation under heavy loading conditions, thereby creating a reduced supply voltage to a power amplifier or other components of the device. For example, due to the reduced supply voltage, an audio output of the amplifier's output stage may be clipped or the audio signal may be reduced in order to prevent the clipping. Such clipping or reduction of the output signal is often not desired. The output of the boost converter is typically captive to a boosted amplifier integrated circuit itself and does not impact any of the other subsystems on the portable device, or risk the potential of a brownout event to the portable device. Thus, a decrease in boosted supply voltage primarily impacts the amplifier and its ability to properly reproduce an output signal on the boosted amplifier integrated circuit.
An example of limiting input power supply consumption of a boost converter consumption by dynamically adjusting the peak current inductor is provided in U.S. patent application Ser. No. 15/229,616, filed Aug. 5, 2016 and entitled “Adjusting Peak Inductor Current to Limit Supply Input Current” (the “'616 Application”), which is incorporated by reference herein. The limiting of input power supply consumption described in the '616 Application may produce a condition in which a boosted supply voltage output by a boost converter is susceptible to loss of regulation.